An in vitro model system to investigate the net flux of alanine and glutamine from skeletal muscle has been developed. Intact m. extensor digitorum longus and m. soleus from Wistar rats were used to study the developmental aspects of the release of alanine and glutamine as well as the dependence of this process on the rate of muscle glycolysis. The release of lysine in this system will be investigated as an index of proteolytic events in muscle. Further investigation into the effects of insulin, glucagon, ketone bodies, and free fatty acids on the release of these three amino acids will be carried out. The observations in these experiments incorporated into the studies of cell free systems, i.e., preparations containing sarcolemma and proteolytic enzymes, will furnish additional information on the nature of amino acid flux from muscle. BIBLIOGRAPHIC REFERENCE: H.R. Zielke, J.T. Tildon, and P.T. Ozand. Glutamine Metabolism in Cultured Fibroblasts. Federation Proceedings, Vol. 34, No. 3, pg. 572, 1975.